WASHINGTON—Acting IRS Commissioner Douglas O’Donnell plans to announce his retirement on Tuesday, said two people familiar with the decision, bringing another abrupt change to a federal agency under stress during its busy period of the year.

The departure comes as the agency faces the crunch of tax filing season and scrutiny from Elon Musk’s initiative.

The official, Doug O’Donnell, a 40-year veteran of the I.R.S., was elevated last month, after the last commissioner stepped down at the beginning of President Trump’s term.

Doug O’Donnell, the acting head of the IRS, is expected to announce his retirement on Tuesday amid turbulence at the tax collection agency, according to a person familiar with his plans. His planned departure comes nearly a week after the Trump administration started laying off thousands of agency workers and following a bid by personnel from the so-called Department of Government Efficiency to gain access to taxpayer data.